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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package hivemall.utils.io;

import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;

import javax.annotation.Nonnull;
import javax.annotation.concurrent.NotThreadSafe;

@NotThreadSafe
public final class NioFixedSegment extends NioSegment {

    private final int recordLength;

    public NioFixedSegment(@Nonnull File file, int recordLength) {
        this(file, recordLength, false);
    }

    public NioFixedSegment(@Nonnull File file, int recordLength, boolean readOnly) {
        super(file, readOnly);
        this.recordLength = recordLength;
    }

    public int readRecords(final long idx, final ByteBuffer buf) throws IOException {
        long ptr = toPhysicalAddr(idx);
        int readBytes = NIOUtils.read(channel, buf, ptr);
        return readBytes == 0 ? 0 : readBytes / recordLength;
    }

    public long writeRecords(final long idx, final ByteBuffer buf) throws IOException {
        long ptr = toPhysicalAddr(idx);
        NIOUtils.writeFully(channel, buf, ptr);
        return ptr;
    }

    private long toPhysicalAddr(final long logicalAddr) {
        return logicalAddr * recordLength;
    }
}